Well to be fair they did have to trade away the farm to win that WS in 2016 and I still don't regret them doing that because with the drought they had going on you had to go all in while you have the best shot to. They haven't done a good job drafting and developing pitchers but if you look at the position talent either on this team still or traded away they did do what they set out to when Theo gutted the mess that he took over which was load up on position prospects and fill in the pitching holes with proven guys either through trade or free agency. You always are going to miss on a few guys but overall they brought in a lot more impact players through the farm system than Jim Hendry did.
The one trade that it looks like we may wind up on the wrong side of was trading Eloy Jimenez for Quintana. Q just hasn't been the pitcher we hoped he would be while Jimenez could be a solid everyday outfielder. I get why they did it at the time, Q was cost controlled starting pitcher the Cubs needed but he just hasn't turned into the top half of the rotation guy he looked like he could be. Had they not won in 2016 I think I would be a lot more sore today about trading Gleyber Torres for a rental closer. Torres is going to be a pretty good player but at the time it looked like he was going to have no where to play without someone changing a position with Russell and Baez having a lock on the middle infield positions. He obviously would be the every day 2B on this team but at the time before Russell's downfall in order to make room for him Baez probably would have had to move to 3B and Bryant to the OF to make room for him when he was ready to come up.
The plan was to build the pitching staff with free agents and trades for a few years, which they did through some terrific trades (Hendricks, Arrieta) and signings (Hammel, Lester, Lackey). It was not to keep relying on trades (Quintana) and signings (Darvish, Chatwood) which have got worse and worse because of a complete inability to develop anything close to an impactful big league arm internally, or even a back end bull pen type. The Cubs have a bottom five farm system now, still nothing at all on the pitching front. The Cubs got Torres and Jimenez simply because they had money to spend in a year several other big market teams didn't in the international pool.
It's also not only about the trades you make, but the ones you don't. Overvaluing Schwarber and Almora has led to the Cubs having one of the worst OF's in all of baseball the last few years. It's extremely easy to find productive bats in the corner OF positions, but between Heyward's contract, and Almora and Schwarber's struggles the Cubs have barely got average value from any OF position. They turned Mike Montgomery, who was a solid spot and very good reliever into a guy the Astro's DFA'd. Obviously Theo is a better GM than Hendry, but Hendry and his love of guys with tools over polish led to Baez and Contreras. I'll be forever thankful for Theo for building the Cubs into a World Series winner but he has loss a lot of his shine over the three years since then. The Cubs looked like they were on the verge of turning into a dynasty in 2016, instead they're closer to an average team than the MLB elites just three years later, which was when Theo expected the team to be peaking.